Pictures Facebook f8 Conference September 22, 2011 / 11:41 AM PDT / CBS News Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook CEO Mark Zuckerberg (Justin Sullivan/Getty Images) Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference (Justin Sullivan/Getty Images) Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook CEO Mark Zuckerberg. (Photo by Justin Sullivan/Getty Images) Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference Facebook Holds Its Fourth f8 Developer Conference